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CHAPTER
THREE
CORE FRAMEWORK
3.1 Object Orientation
3.1.1 Introduction to Object Orientation
qooxdoo allows you to easily leverage many key concepts of object-oriented programming without bothering about
limited native support in JavaScript.
The main actors of qooxdoo OO are:
• Classes
• Interfaces
• Mixins
When trying to get a grip of the framework code, you should probably understand all those three concepts. As a regular
application developer you often get by with ignoring interfaces and mixins when starting and just getting familiar with
classes.
Classes
A “class” is a central concept in most object-oriented languages, and as a programmer you are certainly familiar
with it. qooxdoo supports a “closed form” of class declaration, i.e. the entire declaration is provided within a
qx.Class.define(name, config) statement, where name is the fully-qualified class name, and config
is a configuration map with various keys (or “sections”).
There are several types of classes available, which are specified by the type key within the config map:
• regular class: May contain class variables/methods (in a statics section) and instance variables/methods (in
a members section). An instance of the class can be created using the new keyword, so a constructor needs to
be given in construct.
• static class: Only contains class variables and class methods. Often a helper or utility class. Use type :
"static".
• abstract class: Does not allow an instance to be created. Typically classes derive from it and provide concrete
implementations. type is abstract.
• singleton: Not more than a single instance of the class may exists at any time.
getInstance() returns the instance. Use type : "singleton".
A static method
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